Method of desiccating fluid mixtures



J. C. MAcLACHLAN.

METHOD OF DESICCATING FLUID MIXTURES. APPLICATION FILED AUG.2I. 191s.RENEWED FEB-2,1921.

Patented Nov. 29, 1921.

Q. O J EJ J B mm \9 UNITED STATES PATENT OFFICE.

JOHN C. MAcLACI-ILAN, OF ST. PAUL, MINNESOTA, ASSIGNOR TO STANDARD FOODPRODUCTS COMPANY, OF ST. PAUL, MINNESOTA, A CORPORATION OF DELA- WARE.

METHOD OF DESICCATING FLUID MIXTURES.

Application filed August 21, 1916, Serial No. 115,997.

To all whom it may concern:

Be it known that I, JOHN C. MAoLAoH- LAN, a citizen of the UnitedStates, residing at St. Paul, in the county of Ramsey and State ofMinnesota, have invented certain new and useful Improvements in Methodsof Desiccating Fluid Mixtures, of which the following is aspecification.

My invention relates to the method of desiccating certain fluid mixturessuch as milk, buttermilk, blood, etc., so as to separate the water fromthe solid constituents thereof and retain said solid constituents ingranular form. In the practice of my invention there are two importantsteps; first, to reduce the mixture to a pasty condition by a novelprocess which insures the retention of the original flavor of themixture; and second, to disintegrate the pasty material in heated aircurrents, throwing said material in the form of particles into said aircurrents and subjecting them to the action of the air currents for atime suflicient to withdraw the remaining moisture from thedisintegrated particles and permit the same to be collected as driedgranules.

It is an especial object of my invention to produce such dry granularproduct having the particles of somewhat large, size, as I havediscovered that when dried in that condition milk or buttermilk inparticular retain best the natural flavor and are much more readilyreduced to the liquid form. This is due to the fact that more of thevolatile substance of the milk is held within the pores of the granularparticles after the same have been reduced to the dried form,

The first step of my process as above out lined is important in thatwhile the milk is being thickened to the pasty consistency the volatileelements referred to other than water are retained in the reduced pastymaterial. This is accomplished by introducing the milk in the form ofspray into a regulated current of heated air within a chamber closedexcepting for the air admission and outlet openings, the amount of sprayof milk relative to the current of air being such that the evaportingeffect of the air current will be insuflicient to take away all of thewater of the milk or other mixture. After a given quantity of milk orother mixture has been so treated and the resulting thickened mixturehas accumulated within the container therefor in the chamber I maySpecification of Letters Patent.

Renewed February 2, 19'21. Serial No. 441,995.

still further thicken the mixture by withdrawingihe first accumulationand 1 uting 1t w1th aquantity of milk or other mm mixture, preferablyabout equal volume, and again passing it through the spray condenser.Ordinarily a second operation will produce a mixture of suflicientlypasty consistency, but it is obvious that the operation may be repeatedas often as desired, each tlme resulting in a product having less wateror of more pasty consistency. This method of nnxing the partiallythickened material with'fresh material and gradually reducing theconsistency to pasty form I have found greatly aids in the retention ofthe aforesaid volatile substances and in the consequent high quality ofthe product.

In carrying out the second step of my process I preferably employ arotatable member provided with a number of peripheral projectlonsagainst which the thickened or pasty material is thrown by centrifugalforce, thus physically disintegrating and breaking up the pasty materialinto a mul tiplicity of particles. The action of this apparatus may beregulated so as to break up the pasty material into particles of varyingsizes to be determined by the variable conditions under which theproduct is being made. These particles are thrown radially outwardlyfrom the rotatable. member into a current or currents of heated air,where the same are quickly dried in granular form, the size of granulesbeing regulated by the extent of disintegration as above noted. As thegranules are fully dried they fall by gravity to a suitable collectingspace and are removed in any desired manner.

The full objects and advantages of my invention will appear inconnection with the detailed description thereof and are particularlypointed out in the claims.

In the drawings, illustrating the application of my invention in oneform,-

Figure 1 is a diagrammatic view of the apparatus used in my novelprocess. Fig. 2 is an enlarged sectional detail view of the centrifugalmember employed in my process. Fig. 3 is an elevational sectional Viewon line 33 of Fig. 1.

In the preliminary drying of the milk as it comes in the fresh statefrom the farmer or dairyman I have illustrated a spraying desiccator,though any similar form of device may be used as desired. a The freshmilk is placed in a vat or reservoir 10 where it is fed by gravitythrough a pipe 11 into the spraying nozzle 12 of a desiccator 13. Thisdesiccator comprises a cabinet or casing 14 near one end of which ispositioned a vertical portion 15 extending down from the top to within ashort distance of the bottom thereof. Immediately below nozzle 12 issituated an air inlet 16 through which a current of heated air from afurnace 17 is forced by means of a blower 18 through a pipe line 19. Thetop of cabinet 14 between partition 15 and the adjacent wall of saidcabinet is provided with an air outlet 20. It will now be perceived thatthe spray of milk from nozzle 12 is projected into the stream of heatedair from inlet 16,,and so dried, separating the air and liquid at theportion or baflie 15, the air escaping through vent 20 and the partlythickened milk being deposited at the bottom of the cabinet. By varyingthe volume of air through inlet 16 by means of a damper 21 or by varyingthe fiow of milk through pipe 11 by means of a valve 22 any spissitudeof the milk at the bottom of cabinet 14 can be procured.

At the bottom of cabinet 14 is a p pe 23 which leads up to anddischarges into vat 10. A pump 24 is interposed in this pipe and isadapted to pump the thickened milk from cabinet 14 back into vat 10. Themethod of operation is as follows: The vat 10 is filled with the amountof milk to be desiccated and the same is then allowed to flow into thedesiccator 13 until a certain proportion of the fresh milk remains invat 10. The thickened portion is then pumped back into vat 10 and themixture desiccated to the proper spissitude. This thickened mixture maynow be entirely transferred to the portion of the apparatus for reducingit to the dry form and the above steps repeated, or a portion only ofthe thickened mixture from each batch may be pumped back again and mixedwith a correct proportion of fresh milk. The second expedient causes themixture to contain milk under all stages of con densation up to thefinal degree, while the former provides only the two degrees. The lattermethod has however been found to be the more satisfactory.

The thickened milk upon leaving the desiccator 13 is caused to passthrough a pipe 25 by means of a pump 45 into a hopper 26 of a devicebest shown in Fig. 2, where the same is finally reduced to the dry form.This device comprises a cup-shaped member 27 formed integral with ashaft 28 journaled in a tubular casing 29. Member 27 has attached to ita number of peripheral vanes or blades 30 which have one corner turnedinward at 31. The central portion of member 27 is made to bulge outwardat 32, which portion is provided with a number of diagonallypositionedcircumferentially-disposed holes 33. A feed pipe 34 extends along theupper portion of casing 29 and communicates with the portion 32 at thecenter of member 27. Pipe 34 has screwed into it a trough 35 in which ismounted a screw conveyer 36 and to which is attached the aforementionedhopper 26. lVhen the thickened milk is discharged into hopper 26 throughpipe 25 it is conveyed through the feed pipe 34 against therapidly-rotating member 32, where the same is discharged by centrifugalforce through the apertures 33 in portion 32 against the blades 30 andbroken up into particles of the size desired.

Tube 29 and pipe 34 are provided with a flange 37 by means of which thewhole device may be mounted in a cabinet 38 best seen in Fig. 1. An airline 39 connected with furnace 17 and blower 18 communicates withcabinet 38 through a number of inlets 40 positioned circumferentiallyabout the center of member 27 and extending through the wall of saidcabinet. As member 27 is rotated the milk is tangentially dischargedfrom it in proper-sized particles and a current of air from inlets 40 isforced through the mass of sheet of viscous substance thrown from saidmember and out through a tube 50, thus drying the same to the solidform. Member 27 is remotely situated from the wall of cabinet 38 onwhich it is mounted and is provided with apertures 46 through which airmay enter to relieve the vacuum which would otherwise be produced. Itmay here be mentioned that in order to have the particles of dimensionsgreater than that of powdered form to provide what may be termedgranules, it is necessary to have the milk or substance treated of quitea viscous consistency or of a pasty semi-fluid nature prior to the finaldrying of the same. In such a state it is impossible to break up thesame by any of the usual devices as the substance cannot be sprayed inthe ordinary manner. The degree of heat necessary in this last stage ishence not so great and certain portions of the volatile substance of themilk is maintained within the pores of the granules, giving it a morenatural flavor.

The drive for driving shaft 28 may comprise a pair of spiral gears 41and 42 of which 42 is the driver and is supported on a shaft 43journaled in a bracket 44 secured to cabinet 38. If convenient a highspeed electric motor may be substituted for this arrangement, or anyother form of drive desired.

Hitherto, liquids have been sprayed and dried in the form of powder, butso far as I am aware, I am the first to produce a granular product frompasty or semi-fluid substances. The commercial advantages of thegranular substance over the pulverized substance are very marked.Certain of these advantages have already been stated and are very markedas has been noted. A good granular formation cannot be produced from athin liquid and good granulation cannot be produced even from asemi-fluid or pasty substance, without a beating action. In accordancewith my invent-ion, therefore, the heavy pasty material is discharged insmall particles and thrown violently outward, and as it flies outwardunder the action of centrifugal force, is intercepted and violentlystruck or beaten by the rapidly moving beater blades 30. These beatingblades br ak u or crack 1 )astv substance while it is being rapidlydried in t 1e hot air of the drying chamber and it is, therefore, alsoimportant that this beating action take place in the presence of a hotdrying medium.

The granular products which I have made from sweet milk, buttermilk andmalted milk, for example, are not only of granular form, but of agranular form of peculiar formation. Even as viewed by the naked eye,each granular mass is seen to be made up of a plurality of particles.lVhen one of these granular masses is viewed through a magnifying glassof but low magnifying power, the particles making up the granular massappear to have a crystalline character, and to be of a spongy nature. Itwill be found that these granular masses, by a roller or grindingpressure, may be very easily reduced to powdered form. lVhen, however,they are put into water, even if the water is cold, such granular massesquickly absorb the water, and hence, quickly dissolve and do not form apasty substance with the water. in dissolving powdered substances incold water, for example, and even in warm or hot water, is well known.There is no such difficulty encountered in the use of my improvedgranular product, and moreover as stated, the granular product betterpreserves the original flavor of the material from which the substanceis formed.

The advantages of my invention are manifest. The process is found to bemore economical since more of the original substance is brought downwith the solid matter than is the case in similar processes.

An apparatus very suitable for carrying out this improved process isdisclosed and claimed in my Patent No. 1,801,288, of April 22nd, 1919,entitled Apparatus for granulating semi-fluid materials.

This improved method, as well as the device or apparatus, is especiallyadapted for forming granular substances above stated, but from a broadpoint of view, the process is adapted for producing food products, orthe like, in finely divided form. The important operations foraccomplishing this result are, first, the projecting of the materialoutward under high velocity, and second, in intercepting and beating ofthe same.

The difficulty hitherto encountered It is also highly important thatthis intercepting and beating take place in the presence of a hot orwarm drying medium, such as hot or warm dry air.

I claim:

1. The process of reducing heavy liquid or semi-liquid substances to dryfinely divided form, which consists in projecting the same at highvelocity within a space containinga hot gaseous drying material, and inintercepting and violently beating the same in the presence of said hotgaseous drying medium, by means of blades or striking members that aremoved positively and at high velocity.

2. The process of granulating or finely dividing pasty semi-fluidsubstances, which consists in projecting the same at high velocity andintercepting and beating the same, in the presence of a hot dryingmedium.

3. The process of granulating or finely dividing pasty or semi-fluidsubstances which consists in throwing the same violently outward underthe action of centrifugal force, and in intercepting and beating thesame to granular form by rapidly moving blades or striking members, inthe presence of a hot drying medium.

4. The process of producing from milk a dry granular divided substancewhich consists in delivering substantially all of the milk in a spray orshower through hot air to reduce the same to a heavy viscousconsistency, and thereafter passing such heavy condensed substance againin a spray or shower throughhot air to complete the reduction of thesubstance to a dry divided granular form.

5. The process of producing from milk a dry granular divided substancewhich consists in delivering substantially all of the milk in a spray orshower through hot air to reduce the same to a heavy viscous consistencyand thereafter passing such heavy condensed substance in a spray orshower by centrifugal means through hot air to complete the reduction ofthe substance to a dry divided granular form.

6. The process of producing from milk a 115 dry granular dividedsubstance which consists in delivering the milk in a spray or showerthrough hot air to reduce the same to a heavy viscous consistency andthereafter projecting such heavy condensed substance 120 at highvelocity within a space containing hot gaseous drying material andintercepting and violently beating the same in the presence of said hotgaseous drying medium to complete the reduction of the substance to a125 dry divided granular form.

7. The process of producing from milk a dry granular divided substancewhich consists in delivering the milk in a spray or shower through hotair to reduce the same 180 to a heavy viscous consistency in mixingcomplete the reduction thereof to a dry di- 20 said substance with aquantity of fresh milk and again passing the mixture in a spray orshower through hot air to reduce the same to a heavy viscousconsistency, and thereafter, passing all of such heavy condensedsubstance again in a spray or shower through hot air to complete thereduction of the substance to a dry divided granular form.

8. The process of producing from milk a dry granular divided substancewhich consists in delivering milk in a spray or shower through hot airto reduce the same to a heavy viscous consistency, mixing the heavysubstance with a quantity of fresh milk, then repeating these steps, andfinally passing all of such substance again in a spray or shower bycentrifugal means through hot air to vided granular form.

9. The process of reducing liquid or semiliquid substances containingsolid substances to finely divided form, which consists in deliveringsubstantially all of the said liquid in a spray or shower through hotair to reduce the same to a heavy viscous consistency and thereafterpassing such heavy condensed substance again in a spray or showerthrough hot air to complete the reduction of the substance to a drydivided condition.

In testimony whereof I affix my signature in presence of two witnesses.

JOHN C. MAOLACHLAN.

Vitnesses F. A. WVHITELEY, H. A. BOWMAN.

